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Date: Mon, 28 Apr 2014 12:09:32 -0400
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From: Kevin Stallard <kevin@arilabs.net>
Subject: RE: [LML] Re: Gear Down...INOP
Thread-Topic: [LML] Re: Gear Down...INOP
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Wolfgang,

I am surprised that you remain unconvinced.  Chris' analysis on this topic =
has been the most thorough and careful analysis I've encountered.  He doesn=
't just look at the outside symptoms of the problem, but also delves into a=
spects of the pump and its design (the number of different configurations a=
nd variations available) that I never even considered previously.

I thought it was just a pump, I had no idea that the inner workings had suc=
h an impact on how the system operated until he took the time to take me th=
rough it all. =20

I have had the opportunity to work directly with Chris in a professional se=
tting, I have not encountered a more keen understanding of how things work =
and what questions to ask when things go wrong than that of Mr. Zavatson.  =
He has been able to point out errors in my thinking and how I look at probl=
ems in a way that has been very beneficial to me.  =20

These remarks that you have directed to him concern me greatly.  You aren't=
 asking any questions, you aren't having a discussion, you aren't trying to=
 reconcile the deficit of your understanding of these things, you are attac=
king him personally.  That's where you are losing me.

I'm starting to believe that the  results of someone following your advice =
and using your system could have dangerous if not life threatening conseque=
nces. =20

I think what I would like to see from you is a bit more effort to reconcile=
 your the observations Chris has replicated numerous times on the bench and=
 in the air.  This is what I'm used to seeing when good willed scientists a=
nd engineers disagree.

I have observed Chris quickly change course if evidence is presented that r=
efutes his conclusions.  He is not concerned with being right, he is concer=
ned with what is right, constantly rechecking and questioning his own resul=
ts..  I think you are a very smart and capable individual and we would all =
benefit if you adopted these same principles.

Thank you,
Kevin Stallard
N969RJ  150 hrs and counting!
________________________________________
From: Lancair Mailing List [lml@lancaironline.net] On Behalf Of Wolfgang [W=
olfgang@MiCom.net]
Sent: Monday, April 28, 2014 5:59 AM
To: lml@lancaironline.net
Subject: [LML] Re: Gear Down...INOP

Chris,

I remain unconvinced with your theory. You have suggested that the pump wil=
l somehow shut down immediately after it has started up due to some pressur=
e pulse. The mechanisim of which you have yet to clarify, let alone demonst=
rated.

I'm tired of your kibitzing and since you have proven that you can't let it=
 go, I will and leave you to humor yourself.

Wolfgang

----- Original Message -----
From: Chris Zavatson<mailto:chris_zavatson@yahoo.com>
To: lml@lancaironline.net<mailto:lml@lancaironline.net>
Sent: Saturday, April 26, 2014 1:28 PM
Subject: Gear Down...INOP

Wolfgang,

<<=93I believe in redundancy and it looks like you don't=85.=94>>

I am a big proponent of redundancy.  That is redundancy defined as a true b=
ack-up to an otherwise trouble-free system.

First, I have redundant switches to power the pump solenoids.  This allows =
me to raise and lower the gear in case of the failure of either of the pres=
sure switches.  It doesn=92t happen very often, but it does happen - twice =
in 17 years of flying my 360.

I also have redundant gear down indications.  Two completely separate syste=
ms, separate switches, separate wires and separate indicators.  The second =
set of switches is mounted directly on the over-center links.

I even carry two iPads and a iPhone - just in case

<<=93The pressure pulse you're talking about will subside (glad you agree) =
and as it does, because the cylinder is only partially extended, the cylind=
er will continues to extend, the low switch will close again, and enable th=
e pump to continue . .=94>>

The part you seem to be missing here is that the momentary pulse is not dir=
ectly turning off the pump.  Thus when the pulse subsides, the pump doesn=
=92t just spring back to life.  The pulse pushes the spool in the wrong dir=
ection -against the pump flow.  This locks the poppet that the pump just op=
ened up a fraction of a second earlier.  When this happens, the high side b=
egins to pressurize along with the low side.  As soon as both sides reach t=
he low side pressure setting, the pump is turned off.  This is why you see =
both high and low circuits pressurized to the same value in Lorn=92s photo.

To prevent this, the low side pressure settings should be raised.  800 psi =
has proven sufficient.  The high volume gear pump will reduce the size of t=
he pulse since the higher volume pump is able to absorb incoming fluid at a=
 higher rate.

I highly recommend pressure gauges for both high and low circuit be install=
ed in a location visible to the pilot.  The state of the system can always =
be verified.  One can immediately diagnose any in-flight problem.  Leaks ca=
n be caught early.  And adjusting pressure settings is no longer guess work=
.
Chris Zavatson
N91CZ
360std
www.N91CZ.net=